Improvement of corrosion resistance of AZ91 by lanthanum addition

Addition of Lanthanum improves the stability to the passive film. The stability of the passive film is more in SO₄^2- containing environment than Cl^-. The electrolytes favored the alloy dissolution, but the presence of lanthanum improved the passivity of AZ91 raised the pitting potential greater than the corrosion potential which is in contrast to the generally observed behavior of AZ91 at pH 11. The open circuit potential remains constant and shifts to more active values by increasing the chloride concentration. The preliminary studies indicate the improvement of corrosion resistance of AZ91 by Lanthanum addition.